Thyroid Health in Pregnancy and Autism Risk: What a New Study Actually Shows (and What It Doesn't)
If you're pregnant or planning to be, you've probably already had a thyroid panel drawn at some point without thinking much about it. It's one of those routine prenatal labs that rarely gets explained. A new study out of Israel gives a clearer picture of why that panel matters more than it might seem, while also showing why the headline version of this story ("thyroid problems cause autism") oversimplifies something a lot more nuanced.
What the research found
Researchers followed 51,296 single-baby births at a hospital in southern Israel between 2011 and 2017, tracking which children were later diagnosed with autism spectrum disorder (ASD) and cross-referencing that against their mothers' thyroid function during pregnancy. This is a large retrospective cohort study, not a randomized trial, so it can show associations but can't prove that thyroid dysfunction directly causes autism.
About 8.6% of mothers in the study had abnormal thyroid function at some point. Looking at the group as a whole, autism rates were not meaningfully different between mothers with normal versus abnormal thyroid function. The nuance shows up once you split "abnormal thyroid function" into more specific categories. Chronic hypothyroidism that was already being treated before pregnancy, and therefore likely well-controlled, was not associated with higher ASD risk. What was associated with higher risk was hypothyroidism that developed or went uncontrolled during pregnancy itself, especially the longer it lasted. One trimester of gestational hypothyroidism raised the adjusted risk by about 69%; two trimesters, more than double; three trimesters, more than triple. In other words, this isn't a story about thyroid disease being dangerous. It's a story about unmanaged thyroid disease during pregnancy being the variable that matters, with a clear dose-response relationship: the longer it went uncontrolled, the higher the association.
The bigger picture
This finding fits into a body of research that is a real mix, and it's worth naming that plainly rather than cherry-picking the parts that confirm one narrative. A 2024 narrative review in the journal Thyroid pooled the existing human studies and concluded that the evidence leans toward a positive association between maternal thyroid dysfunction, particularly hypothyroidism, and ASD outcomes, while cautioning that misclassification bias (many studies rely on medical records rather than lab values) and publication bias could be inflating that signal. Not every study agrees. A large Danish cohort of nearly 18,000 mother-child pairs, published in the same journal as the Israeli study, found no association at all between first-trimester maternal thyroid hormone levels and either ASD or ADHD in the children, even after stratifying for pre-existing thyroid disease. A smaller but more recent prospective study out of China, following 100 mother-child pairs, did find that isolated low thyroxine in the first trimester was linked to lower developmental scores and higher scores on autism and ADHD screening tools.
On the mechanistic side, animal research offers a plausible "why." A 2024 mouse study found that inducing low thyroid hormone during pregnancy produced autism-like behaviors and inflammatory changes in the offspring's brains, and that supplementing the mothers with thyroid hormone during the exposure window prevented those changes from developing. That's exactly the kind of biological mechanism you'd want to see if the human association is real, but it's a mouse study, and mouse brains are not human brains. It's supporting evidence for plausibility, not proof of what happens in people.
The naturopathic lens
Studies like this one confirm something I already emphasize with patients: thyroid screening in pregnancy isn't a box to check once and forget. Thyroid hormone needs shift throughout pregnancy, iodine requirements go up, and a lab value that was normal preconception can drift during the second or third trimester without any obvious symptoms. The dose-response pattern in the Israeli study, where risk climbed the longer thyroid dysfunction went unmanaged, points toward monitoring and timely treatment as the actual lever here, not thyroid disease itself as some kind of verdict.
This is squarely a collaborative-care situation, not a naturopathic-alone one. If you're pregnant and have a personal or family history of thyroid disease, I'd want you working with both your OB or midwife and, ideally, an endocrinologist who can track your labs across all three trimesters, not just once. Where a naturopathic visit adds value is in the surrounding picture: iodine and selenium status, autoimmune thyroid markers if there's a family history of Hashimoto's, and making sure nothing in your diet or supplement routine is working against thyroid function without your knowledge.
What this means for your next appointment
If you're pregnant or trying to conceive, ask your provider whether thyroid function will be rechecked later in pregnancy, not just at the first visit, especially if you have any personal or family history of thyroid disease. Don't stop or adjust thyroid medication on your own if you're already being treated. If you're autistic yourself, or parenting an autistic child, please know this isn't a study about blame; it's about identifying a manageable variable in an enormously complex picture of neurodevelopment, most of which has nothing to do with maternal thyroid function at all. If anything, the most useful takeaway is the boring one: consistent monitoring throughout pregnancy, not just early on, appears to be the piece that's actually in your control.
References
Original article: "Maternal Thyroid Dysfunction and Risk of Autism Spectrum Disorder." https://www.medpagetoday.com/reading-room/endocrine-society/diabetes/122283
Elbedour L, Weinberg M, Meiri G, Michaelovski A, Menashe I. Maternal Thyroid Hormone Imbalance and Risk of Autism Spectrum Disorder. J Clin Endocrinol Metab. 2026;111(5):e1412-e1420. PMID: 41288361. doi:10.1210/clinem/dgaf596
Kaplan ZB, Pearce EN, Lee SY, Shin HM, Schmidt RJ. Maternal Thyroid Dysfunction During Pregnancy as an Etiologic Factor in Autism Spectrum Disorder: Challenges and Opportunities for Research. Thyroid. 2024;34(2):144-157. PMID: 38149625. doi:10.1089/thy.2023.0391
Møllehave LT, Grand MK, Kriegbaum M, et al. Maternal Thyroid Function in Early Pregnancy and Offspring School Performance and Neurodevelopmental Disorders. J Clin Endocrinol Metab. 2025;110(4):e1000-e1008. PMID: 38781538. doi:10.1210/clinem/dgae358
Du J, Xu X, Yuan N, Zhang X. Effect of maternal isolated hypothyroxinemia in the first trimester on offspring neurodevelopment: a prospective cohort study. Front Endocrinol (Lausanne). 2026;17:1734708. PMID: 41788780. doi:10.3389/fendo.2026.1734708
González-Madrid E, Rangel-Ramírez MA, Opazo MC, et al. Gestational hypothyroxinemia induces ASD-like phenotypes in behavior, proinflammatory markers, and glutamatergic protein expression in mouse offspring of both sexes. Front Endocrinol (Lausanne). 2024;15:1381180. PMID: 38752179. doi:10.3389/fendo.2024.1381180 (animal study)
Disclaimer
This article is for educational purposes only and does not constitute medical advice. Thyroid management during pregnancy should always be directed by your OB, midwife, or endocrinologist. Please don't start, stop, or change any thyroid medication without talking to the provider managing your care.
If this resonates with what you're experiencing and you'd like to explore a naturopathic approach, book a consultation with our clinic.
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